code: def test_serialize_zoom_center(self):
      viewport = maps.InitialViewport.from_zoom_center(3, (20.0, -5.0))
      expected = {
          "type": "ZOOM_CENTER",
          "center": (20.0, -5.0),
          "zoom_level": 3,
      }
      assert maps._serialize_viewport(viewport, None) == expected
  
file_path: gmaps/gmaps/tests/test_maps.py
imports: import unittest
  import traitlets
  from ..None import maps, heatmap_layer
label_desc: Use image node_id 2 for calling the SerializeViewport obj's underlying member method code with example usage: obj.test_serialize_zoom_center() without return types